> For the complete documentation index, see [llms.txt](https://docs.notionapps.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.notionapps.com/frequently-asked-questions/why-are-my-rollups-on-notionapps-showing-zero-0-value-or-an-incorrect-value.md).

# Why are my rollups on NotionApps showing zero (0) value or an incorrect value?

## Reason #1

When rollups are used with `average, min, max, sum` and other such calculations, Notion does not return the correct value of these rollups to NotionApps. 

In these cases, we suggest using a Formula instead of a Rollup. You can re-create `average`, `min`, `max`, and `sum` calculations with formulas. 

For example, to calculate the average number of days each Project's Tasks  take, you could create a formula like so:

```
sum(prop("Tasks").map(current.Days))/prop("Tasks").length()
```

To calculate the minimum number of days each Project's Tasks take, you could create a formula like so:

```
min(prop("Tasks").map(current.Days))
```

## Reason #2

Another common reason for incorrect Rollup or Formula data is because NotionApps does not have access to all the databases involved in the calculations.

#### **Example Scenario**

Suppose you have two databases:

* Projects
* Tasks

You’ve set up a Formula property in the Projects database (for example, “# of tasks completed”) that counts how many tasks in the Tasks database have a “Completed” status.

If NotionApps only has access to the Projects database (but not the Tasks database), Notion will return a value of 0 for the formula, even if there are completed tasks. This happens because NotionApps doesn’t have permission to read the relevant data from Tasks.<br>

#### **How to Fix**

To ensure accurate data for Rollup and Formula properties:

1. **Grant NotionApps access to all related databases.**

   Make sure NotionApps is authorized to access **every** database referenced by your Rollup or Formula properties (if you'd like to use those properties in the app).
2. **How to update database access:**
   * Go to your **Account Settings** and click on **Manage Databases**

     OR
   * Open your app builder in NotionApps, visit the **Databases** tab, and click on **Manage Databases**
3. Select the related databases.

After updating access, click on the **Reload Data** button in your app builder. NotionApps will be able to fetch the correct values for all your Rollup and Formula properties.

## Reason #3

Sometimes Notion does not return the correct formula/rollup value because it loads the data in a lazy manner. To solve this, add an additional property representing the same information.&#x20;

* If your existing property that's showing the incorrect value is a Rollup property, add a Formula property to pull the same information.&#x20;
* If your existing property that's showing the incorrect value is a Formula property, add a Rollup property to pull the same information.&#x20;

This forces Notion to pull the property data before sending it to us.

If you have any questions, please reach out to us at <help@notionapps.com>.&#x20;